Chewable toy for animal

ABSTRACT

A super-tough molded elastomeric chewable polyurethane toy for an animal. The toy may be shaped to simulate a dog bone and to make swallowing difficult when being chewed. It is also chemically inert in the animal&#39;s digestive system and is characterized by moderate hardness, resilient deformability, large tensile strength and resistance to shearing. It is generally slightly heavier than water, but may be foamed or impregnated with air to float. The toy also makes use of a unique property of polyurethane whereby a surface-migrating flavoring pleasing to the animal is mixed with the polyurethane composition while the latter is in a liquid phase prior to being molded to the desired shape. Thus as the flavoring is chewed off or otherwise dissipated from the exterior surface of the toy, the flavoring is continuously replenished.

This invention relates to a chewable toy or simulated bone for ananimal, which is highly resistant to destruction by being chewed and isharmless if swallowed, and in particular relates to such a toycomprising an aromatic flavored polyurethane appealing to the animal,and to a method for making the toy.

BACKGROUND AND OBJECTS OF THE INVENTION

Numerous chewable toys for animals fabricated from rubber, plastics,rawhide and the like have long been available for the purpose ofmassaging the gums and strengthening the teeth of the animal, but eachsuch toy has been subject to various objections, such as the inherentbad taste of rubber, susceptibility to destruction when chewed, andhardness or brittleness, as for example when made from Nylon® whichcould damage the animal's teeth. The rawhide "bone" has been in commonuse, but it disintegrates rapidly when chewed, and like some of theplastics used heretofore, large sections can be torn away and ifswallowed can get caught in the dog's throat.

An important object of the present invention has been to provide animproved durable chewable toy or "bone" for pets, which avoids theabove-noted objections, which may be molded from polyurethane tosimulate a real bone having an elongated body with enlarged bifurcatedends to provide chewing protuberances for small dogs and curved exteriorsurfaces adapted to conform to and massage the gums of larger dogs, andwherein the elongated body curves in opposite directions from itsmid-region to effect oppositely directed compound or three-dimensionalcurvatures, which in cooperation with the enlarged ends preventaccidental swallowing of the simulated bone by large dogs.

Another object is to take advantage of the unique physical properties ofpolyurethane to provide such a toy, which can be a ball or other shapeas well as a simulated bone in appearance and which is molded from anelastomeric polyurethane to provide a super-tough toy highly resistantto chewing and in fact essentially indestructible by chewing except byvery large dogs, wherein the polyurethane itself is odorless, tasteless,and chemically inert in the digestive system so as to be harmless ifswallowed. The polyurethane has a moderate hardness durometer to assurethe desired flexibility and compressibility in a chewable toy, so as tomassage a pet's gums without undue wearing of the teeth and to provide atoy that can be caught in the air by a dog for example without breakingthe dog's teeth, in contrast to similar bones of hard material such asNylon® which can chip a dog's teeth. On the other hand, the polyurethanealso has large coefficients of tensile strength and resistance toshearing to enable the toy to be stretched twisted and compressed withinthe limits of its elasticity by sharp teeth and strong jaws withoutdisintegrating while being chewed, so as to outlast comparable toys ofrubber, rawhide and even Nylon®, and has the resiliency to enable returnof the toy essentially to its undeformed condition after being chewed.

Another object is to provide a molded polyurethane toy or "bone" of theabove character impregnated with air bubbles so as to be lighter thanwater and useful for example in water games with a dog or for training adog to retrieve. Although the aerated bone is more readily destroyed bychewing, it is somewhat softer and more spongy and is thus ideal forolder dogs.

Another object is to provide an improved chewable polyurethane toy ofthe above character having a surface-migrating flavoring agreeable tothe animal and uniformly distributed throughout the volume of the toy,whereby as the surface flavoring is removed during the chewing process,the flavoring is replaced at the surface by flavoring from the interiorof the toy.

Another object is to provide an improved method of manufacturing such atoy wherein an aromatic extract such as catnip or a meat flavoring isadded to and uniformly distributed throughout the polyurethane materialto comprise a homogenous portion of the toy.

Another and more specific object is to add the aromatic flavoringextract during the initial formulation of the polyurethane, whereby theextract is thoroughly mixed with the components of the polyurethane,first during the mixing of said components during the initialformulation, and thereafter during the granulation and mixing of thepolyurethane in preparation for the final moldingoperation. By virtue ofthe foregoing, a thorough mixing of the extract within the polyurethaneis assured and the necessity of providing a specific mixing procedurefor mixing the extract within the polyurethane is eliminated. Inasmuchas the components in the formulation of the polyurethane must bethoroughly mixed in any event, the same mixing procedure is utilizedboth for mixing the polyurethane components with themselves and formixing the extract with the components. The flavoring extract is usuallyhighly concentrated, such that thorough mixing is important. Otherwiselocalized concentrations of the extract can overpower the sensory nervesof the animal and effect a disagreeable reaction rather than theintended taste or aroma that is pleasing to the animal.

Where the extract loses its aroma or flavor in consequence of heating,the flavoring extract is initially added and thoroughly mixed with thegranulated polyurethane when the latter is heated and melted immediatelyprior to the molding operation. A satisfactory distribution of theextract can be accomplished by such a procedure and the extract is onlysubjected to a single heating cycle, i.e., the heating required to meltthe polyurethane prior to the molding. The extract is spared the heat ofthe exothermic reaction resulting from mixing the aforesaid componentsduring the formulation of the polyurethane.

In some conventional molding operations, the polyurethane comprises twoor more liquid components that are mixed by being fed simultaneously atmeasured rates directly into the mold. In such instances the liquidflavoring extract is likewise fed into the mold along with the liquidcomponents to effect a thorough mixing of the liquid extract andcomponents for the polyurethane in a single mold filling operation.

THE PRIOR ART

The prior art is replete with molded pet toys and dog bones, but theconcept of utilizing the unique properties of polyurethane to provide atoy or dog bone as described herein, or of providing such a toy having asurface-migrating flavoring extract homogenously distributed throughoutthe polyurethane as a part of the toy, and the fabrication of the toy bymixing the flavoring extract with the liquid components of thepolyurethane during the initial formulation of the latter, as describedherein, is nowhere suggested by the art known to applicant.

U.S. Pat. Nos. to Bruler, 2,194,736; Jones, 2,610,851; Fisher,3,104,648; and Axelrod, 3,871,334 are typical of the known art. Bruler,for example, discloses a "bone" molded from a porous elastic materialsuch as rubber. A material that gives off an odor agreeable to a dog maybe placed in a hollow part of the porous material. Jones, Fisher andAxelrod similarly disclose a toy of rubber or other resilient material,including Nylon® and resin, that may be conventionally flavored toentice the dog. There is no hint in these patents of utilizing thesuperior characteristics of polyurethane to provide an essentiallyindestructible and harmless bone, nor of how the toy is flavored, exceptthat it is conventionally flavored, meaning a surface coating orimpregnation under pressure, as in Axelrod, which is a costly and timeconsuming procedure, or the insertion of aromatic pellets into a hollowchamber of a porous toy, which by reason of its porosity is also readilydestroyed when chewed or gnawed.

Other objects of this invention will appear in the following descriptionand appended claims, reference being had to the accompanying drawingsforming a part of this specification wherein like reference charactersdesignate corresponding parts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a dog bone embodying the presentinvention.

FIG. 2 is a bottom view of the bone of FIG. 1.

FIG. 3 is a transverse section through the midregion of the bone of FIG.1.

FIG. 4 is a side view of the bone of FIG. 1.

It is to be understood that the invention is not limited in itsapplication to the details of construction and arrangement of partsillustrated in the accompanying drawings, since the invention is capableof other embodiments and of being practiced or carried out in variousways. Also it is to be understood that the phraseology or terminologyemployed herein is for the purpose of description and not of limitation.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings, a dog bone embodying the present inventioncomprises an elongated central portion 10 having enlarged opposite endportions 11 and 12 bifurcated to provide a pair of flared endwiseenlarging projections 11a and 11b spaced by a notch 11c at the enlargedend 11, and similar flared endwise enlarging projections 12a and 12bspaced by a notch 12c at the opposite enlarged end 12. The mid-region atthe upper or top portion of the bone in FIG. 1 is provided with anupwardly opening channel or groove 13 that extends the major length ofthe portion 10. From the upper portions of the walls of the groove 13,the lateral surfaces of the bone diverge from each other approximatelyto the longitudinal mid-regions 14 of the opposite lateral surfaces,which surfaces then converge downwardly toward each other to a centrallylocated lowermost or bottom ridge 15, thereby to provide a somewhatheart-shaped cross section, FIG. 3.

By comparing FIGS. 1 and 4, it may be observed that the bone curvesthree-dimensionally in oppositely directed compound curvatures from itstransverse mid-region to its enlarged ends 11 and 12. From the aforesaidtransverse mid-region in FIG. 1, the longitudinal portion 10 curves at16 downwardly toward the end 11. Similarly the longitudinal portion 10curves at 17 upwardly from its transverse mid-region toward the enlargedend 12. The concave surfaces of the curvatures 16 and 17 curvecontinuously with the surfaces of the flared end portion 11b and 12brespectively, whereas the convex surfaces of the curvature 16 and 17recurve slightly at their junctures with the surface of the flared endportions 11a and 12. The upper surfaces of the end portions 11 and 12curved upwardly and the lower surfaces of end portions 11 and 12 curvedownwardly in the endwise directions. The complex curvature describedprovides a bone that is difficult to swallow. If one end of the bonedoes enter a dog's throat, it may be readily pulled out by the dogholding the enlarged outer or opposite end of the bone with the pawswhile pulling the head backward, which apparently is an instinctivereaction.

The paired bifurcated end portions 11a, 11b and 12a, 12b are flaredendwise to provide chewable extensions that can be gripped in the mouthof a comparatively small dog. The total transverse sectional area ofeither pair of projections 11a, 11b or 12a, 12b is approximately equalto the area of the transverse section through the longitudinal portion10, FIG. 2. By virtue of the notches 11c and 12c, either of the pairedextensions 11a, b or 12a, b can be bent resiliently toward each other inthe chewing process within their limits of elasticity, and the partswill return to their undeformed shapes after being chewed. Also thebifurcated projections can be readily received between the jaws of adog, and by virtue of the curvature of the bone 10 adjacent its endportions, the lateral and mesial surfaces of the bone will engage andmassage both the labial and lingual gums of the dog during the chewingprocess.

The groove or channel 13 reduces the total cross-sectional mass of thepolyurethane material similarly to the action of the grooves 11c and12c, and facilitates flexing of the upper portions of the bone portion10 at opposite sides of the groove 13 to provide a satisfying crunchingeffect to the chewer even if the bone is fabricated from a comparativelyhard elastomer that would otherwise have very little yieldability whensubjected to a normal chewing force.

Although the bone shaped as described above can obviously be molded fromany of the elastomeric materials utilized heretofore for such toys, animportant concept of the invention is the use of a preferred elastomercomprising a polyurethane having among other qualities the uniquedistinction of being essentially indestructible by ordinary chewingforces; will yield resiliently within its limits of elasticity andreturn to its undeformed condition when the deforming force isterminated; and is extremely resistant to shearing by sharp teeth thatwould normally disintegrate elastomers used heretofore, such as thevarious rubber-like compounds, resins, and polyethylenes.

Animal toys of various shapes and sizes, including the above-describedbone shape, various other bone shapes, and spheres or balls have beenformed in accordance with the present invention from polyurethaneshaving a hardness or durometer ranging between approximately 35 and 60Shore D as measured by ASTM (American Society of Testing Materials) Test2240; an ultimate tensile strength between approximately 20 and 25 MPa(Mega Pascals) measured by ASTM Test D 412; an ultimate elongationranging between approximately 500% and 600%; a tensile strength betweenapproximately 6.9 and 16.5 MPa at 100% elongation; and betweenapproximately 10.3 and 19 MPa at 300% elongation; a tensile set ofapproximately 3% to 18% at 50% elongation; a tear strength of betweenapproximately 80 and 140 kN/m (kilo Newtons per meter) measured by ASTMTest D 624-Die C; and a compression set of between approximately 30% and40% at 70° C. over a 22 hour period.

Polyurethanes having physical properties within the ranges specifiedabove are usually satisfactory for chewable animal toys and arepreferred for typical situations. However, the durometer range can bewidened to between 10 and 80 Shore D where desired, and such widening ofthe hardness range will obviously widen the ranges for other physicalcharacteristics such as tensile strength, elongation, tensile set, tearstrength, and compression set.

The preferred polyurethanes having the physical characteristicsenumerated above are slightly heavier than water and have specificgravities ranging between 1.1 for the softer polyurethanes, and 1.2 forthe harder polyurethanes. Another concept of the present invention is toprovide a toy as described herein useful in water sports or for trainingan animal to retrieve. Accordingly foaming agents are employed or airbubbles are blown or worked into the polyurethane by conventiona duringthe molding operation to provide a floating toy lighter than water.

Although animals accustomed to gnawing and chewing will chew onpolyurethane toys which in themselves are tasteless and odorless,another concept of this invention is to increase the attractiveness ofsuch toys to animals by utilizing additional unique characteristics ofthe polyurethanes and to flavor the toy with flavoring or aromatic oilswhich are dispersed uniformly and preferably homogenously throughout thetoy in accordance with the process described below to provide a flavorthat will remain appealing to the animal without appreciable diminishingeffectiveness essentially for the life of the durable polyurethanematerial of the toy.

Polyurethanes are characterized by the urethane linkage (--NH--C═O).This typical linkage is formed by the reaction of an isocynate group(R--N═C═O) with a hydroxyl containing compound (R--OH). While reactionwith a hydroxyl compound is primary, isocyanates will also react withany compound containing an active hydrogen atom. Therefore functionalgroups such as the urea, amide, allophanate, biuret, and other groupsmay become important parts of the polyurethane polymer. In addition,most of the hydroxyl containing compounds are polymers in themselves.These are generally polyethers and polyesters, but other hydroxylcontaining polymers, such as castor oil, can be part of the polyurethanecomplex.

In formulating a urethane compound, there are several different types ofmaterials that either must be or can be used. These materials cangenerally be classified into the following: isocyanates, polyols, chainextenders, catalysts, blowing agents, functional additives, fillers, andnon-functional additives. All of these, with the exception of thefillers and non-functional additives, comprise the polymer network wheretheir independent structures react into and become an integral part ofthe resultant urethane polymer. This polymer structure is responsiblefor the basic physical nature of the polyurethane, i.e., its strength,elasticity, toughness, resiliency, and other physical characteristics.

Fillers and non-functional additives do not enter into the polymerreaction, but do affect the physical nature of the final urethanecompound. Although these latter additives are not reacted or chemicallybound to the polymer structure, they are held by the polymer structureby physical entrapment and, in some cases, by secondary chemicalassociation.

Examples of these latter additives are colorants or pigments,non-reactive blowing agents, fillers such as calcium carbonate, clays,mica, and others, and lubricants. Most of these additives arepermanently locked into the polymer structure, but some are actuallyinsoluble and incompatible in the urethane compound. The incompatibilitymight be due to the urethane groups present or to other of the manyfunctional groups present. In any event, the insolubility of suchadditives causes the same to work gradually to the surface of thepolyurethane.

Traditional examples of such surfacing of insoluble or incompatiblecomponents are referred to as "bloom" wherein a pigment or colorant isprovided in a wax or oil-based carrier that migrates to the surface toform an off-color haze. The haze can generally be wiped off, but willreturn with time; and "self-lubrication" wherein an oil formulated intoa polyurethane compound continually migrates to the surface. If thesurface is cleaned, the oil will reappear in time.

Flavors or odors, hereinafter referred to as "aromatic extracts", arecomplex organic compounds that can be soluble in many oils. Some of thearomatic extracts function as surface-migrating substances. Theincompatibility of the urethane compound and the aromatic extract couldpossibly be due to the extract's basic chemical structure, or to thegreater solubility of the aromatic extract in its oil or wax carrier,which in turn is incompatible with the polyurethane and conveys theextract to the surface.

The migrating nature of the oil-based aromatic extract makes theflavored urethane unique. The aromatic extract can be added to many ifnot all plastics, but to be effective the molecules of the aromaticextract must be available at the surface of the chewable toy. In mostplastics, when the flavoring molecules on the surface are removed, theflavor or aroma is lost regardless that many other flavoring moleculesmay still be locked in the plastic. In the flavored urethane, when thesurface molecules of the flavoring are removed, they are replaced by newflavoring molecules migrating from the compound's interior.

The rate of migration is a function of various factors, includingtemperature and the polymer molecular activity. The temperature andmolecular activity is increased by the frictionally induced build-up ofinternal energy resulting from bending, flexing and compressing the toy.Therefore such actions as chewing and the body heat of the animal'smouth can increase the migration of the aromatic extract to the surface,thereby increasing the satisfaction of the chewer. An animal can learnthat the harder it chews, the more satisfying will be the taste.

In the manufacture or fabrication of an animal toy embodying the presentinvention, the various above-noted components known to be required forthe formulation of a polyurethane having the desired physicalcharacteristics specified herein are mixed together in measuredquantities while in a liquid phase, thereby to initiate an exothermicreaction resulting from the polymerization of the components. Theinitial reaction in the liquid phase requires but a few minutes untilsolidification takes place. During the initial mixing of the liquidcomponents and while these are still in the liquid phase, the aromaticextract, usually in a wax or oil carrier, is added as a liquid orpulverized solid and also mixed thoroughly with the reacting components.The extract may be any of numerous flavoring extracts known to the artand incompatible with the polyurethane to effect the surface-migratingaction as noted above. The flavoring itself can be a surface-migratingsubstance of the type described above, i.e., incompatible with theresulting urethane compound, or it may be highly soluble in its oil orwax carrier, which in turn must be non-compatible with the resultingurethane so as to migrate with the flavoring to the surface of the toy.The incompatibility referred to herein thus pertains tosurface-migrating substances that apparently do not combine chemicallywith the components that form the polyurethane.

The flavor or aroma of the extract will, of course, be agreeable to theanimal for which the toy is intended and may impart a meat or catnipflavor or aroma, for example. Only a small quantity of the extract isrequired, amounting usually to about one-half of a percent by weight ofthe total composition. Accordingly if a wax carrier is employed thesmall quantity of wax is quickly melted by the reaction heat anddispersed uniformly throughout the liquid components in the reaction andis thus distributed homogenously throughout the resulting solidifiedpolyurethane.

The solidified polyurethane is then generally cured for a few days toassure stabilization of the reaction or polymerization process, althoughthe reaction can be adjusted by means known to the art to permitstabilization more rapidly. The cured polyurethane is then ground intogranules and fed preferably to an injection molding machine wherein thegranules are heated and melted and finally injected under pressure in aliquid form into an injection molding die. Although the toy in manyshapes can be molded conventionally at atmospheric pressure,conventional injection molding is preferred because of the speed of themolding cycle and the versatility of the process that enables theformation of essentially any shape desired.

In the process known as Reaction Injection Molding (RIM) the compositionof the polyurethane is selected to avoid the aforesaid few days curingtime. In such a process the liquid components for the polyurethane arethoroughly mixed by being simultaneously injected at measured rates intoa mixing head of an injection molding machine from which the mixedcomponents are then forced into a die to form the finished chewable toy.In such a process, the flavoring extract is also added at a measuredrate into the mixing head simultaneously with other components for thepolyurethane. In a variation of RIM known as casting, the flavoringextract and liquid components are poured simultaneously into an openmold at atmospheric pressure, whereby the components and extract arethoroughly mixed as they are poured into the mold that forms thechewable toy. In the latter process, as well as in the RIM process, theprimary curing takes place in the mold and may continue for a limitedtime after the toy is removed from the die or mold.

Alternatively to adding the flavoring extract during the mixing of theinitial liquid components from which the polyurethane is formulated, theextract can be added to the cured granules and thoroughly mixedtherewith prior to the injection molding process. Such a procedurerequires an additional mixing procedure which is avoided in the firstmethod described above and for that reason is usually not preferred. Incertain instances, as for example where the flavoring tends to bedecomposed by the heat of the exothermic reaction, the secondalternative procedure may be preferred.

It is apparent from the foregoing that a particularly durable,long-lasting chewable toy for an animal has been provided in combinationwith a flavoring that is satisfying to the animal and capable of beingreplenished at the surface of the toy over an extended time period whichfor all practical purposes will usually equal the life of the toy. Thetoy is non-toxic, has superior toughness, resistance to shearing, andexcellent elasticity that enables it to return to its original shapeafter being chewed. The polyurethane can be comparatively soft, can becaught in the air by a dog without breaking a tooth, does not splinter,and cannot be torn apart except by unusually large dogs. Even if a partis pulled loose by a dog, it does not present sharp edges and passesreadily through the digestive system intact and without harm to the dog.

In regard to brittleness, polyurethanes retain their elasticity orchewability for years and resist "drying out" or hardening and becomingbrittle, as compared to rubber-like materials or resins used heretofore.Likewise, by virtue of the surface-migrating aspect of the flavoringextract dispersed uniformly throughout the toy, the extract does not dryout within the body of the toy and is continuously replenished at thesurface of the toy if the surface extract dries during an extended timewhen the toy is not in use.

I claim:
 1. A molded one-piece polyurethane dog bone having an elongatedbody and enlarged opposite end portions; said bone having oppositelateral surfaces and upper and lower surfaces curving in compoundcurvatures; said curvatures comprising said upper and lower surfaces ofsaid elongated body extending in one direction from the mid-region ofsaid body curving upwardly, the upper and lower surfaces of said bodyextending in the opposite direction from said mid-region curvingdownwardly, the upper and lower surfaces of the end portion in said onedirection curving upwardly and downwardly respectively, the last namedupper surface comprising a continuation of the upward curvature of saidupper surface of said body, the last named lower surface recurvingdownwardly from the upward curvature of said lower surface of said body,the upper and lower surfaces of the end portion in said oppositedirection curving upwardly and downwardly respectively, the last namedupper surface recurving upwardly from the downward curvature of saidupper surface of said body, and the last named lower surface comprisinga continuation of the downward curvature of said lower surface of saidbody.
 2. A polyurethane dog bone according to claim 1, each saidenlarged end portion bifurcating laterally and extending endwise fromthe associated end of said elongated body for approximately one-thirdthe length of said bone from said mid-region to said associated end. 3.A polyurethane dog bone according to claim 2, the total transversesectional area of the two bifurcated end portions of said bone at eitherend thereof being on the order of magnitude of the transverse sectionalarea of said longitudinal body.
 4. A polyurethane dog bone according toclaim 2, said elongated body being generally heart shaped in transversesection to provide a centrally located upwardly opening channelextending along its upper surface and a centrally located ridgeextending along its bottom surface.
 5. A polyurethane dog bone accordingto claim 4, the depth of said channel being approximately one-third thedistance between said upper and lower surfaces.
 6. A polyurethane dogbone according to claim 5, the total transverse sectional area of thetwo bifurcated end portions of said bone at either end thereof beingapproximately equal to the transverse sectional area of saidlongitudinal body.
 7. A chewable toy for an animal, said toy comprisinga molded elastomeric polyurethane material containing asurface-migrating flavoring extract dispersed within the molecularstructure of said material.
 8. A chewable toy according to claim 7,comprising the product of adding said extract to the polyurethanematerial when the latter is in a liquid phase prior to being molded. 9.A chewable toy according to claim 7, comprising the product of addingsaid extract during the formulation and mixing of the polymerizableliquid components of said polyurethane.
 10. A chewable toy according toclaim 7, said toy comprising a one-piece simulated bone having anelongated body and enlarged opposite end portions; said bone havingopposite lateral surfaces and upper and lower surfaces curving incompound curvatures; said curvatures comprising said upper and lowersurfaces of said elongated body extending in one direction from themid-region of said body curving upwardly, the upper and lower surfacesof said body extending in the opposite direction from said mid-regioncurving downwardly, the upper and lower surfaces of the end portion insaid one direction curving upwardly and downwardly respectively, thelast named upper surface comprising a continuation of the upwardcurvature of said lower surface of said body, the upper and lowersurfaces of the end portion in said opposite last named upper surfacerecurving upwardly from the downward curvature of said upper surface ofsaid body, and the last named lower surface comprising a continuation ofthe downward curvature of said lower surface of said body.
 11. Achewable toy according to claim 10, each said enlarged end portionbifurcating laterally and extending axially endwise from the associatedend of said elongated body for approximately one-third the length ofsaid bone from said mid-region to said associated end, the totaltransverse sectional area of the two bifurcated end portions of saidbone at either end thereof being on the order of magnitude of thetransverse sectional area of said longitudinal body.